The most common and most likely answer to this crossword clue is the 7 letter word MORDANT
I've seen this crossword clue in The Daily Telegraph
M
O
R
D
A
N
T
More clues leading to the result MORDANT
- Fixer of great deal, securing honoured sportsman?
- Waspish matron fussing round head of department
- Larger amount of Italian poet, never seeing English as incisive
- Waspish matron bustling about end of ward
- It’s biting as Spooner’s sleeping?
- Biting insect squashed by medic on street
- Sharp matron bustling round ward, finally
Buddy explains!

The straight part
We know that "Waspish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case waspish = mordant.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does MORDANT mean?
MORDANT noun- Any substance used to facilitate the fixing of a dye to a fibre; usually a metallic compound which reacts with the dye using chelation.
- Any corrosive substance used in etching.
- A glutinous size used as a ground for gilding, to make the gold leaf adhere.
- To subject to the action of, or imbue with, a mordant.
- Having or showing a sharp or critical quality
- Serving to fix a dye to a fibre.